A common 3D display device comprises a display panel and a liquid crystal lens arranged on a light exiting side of the display panel, the 3D display device forms a plurality of viewing regions on the light exiting side of the display panel by using the liquid crystal lens, so that light emitted from different pixel units of the display panel can go into different viewing regions, resulting in a 3D sense.
An existing liquid crystal lens, as shown in FIG. 1a, comprises: a first substrate 1 and a second substrate 2, arranged opposite to each other; a liquid crystal layer 3, disposed between the first substrate 1 and the second substrate 2; first electrodes 4, disposed on a side of the first substrate 1 facing the liquid crystal layer 3; a first alignment layer 5, located on a side of the first electrodes 4 facing the liquid crystal layer 3; a second electrode 6, located on a side of the second substrate 2 facing the liquid crystal layer 3; a second alignment layer 7, located on a side of the second electrode 6 facing the liquid crystal layer 3; a first polarizer 9, located on a side of the first substrate 1 away from the liquid crystal layer 3; and a second polarizer 10, located on a side of the second substrate 2 away from the liquid crystal layer 3, wherein, generally, the first electrodes 4 are designed into strip electrodes, and the second electrode 6 is designed as a plane electrode. The liquid crystal lens may be divided into a plurality of liquid crystal lens units, and each of the liquid crystal lens units comprises a plurality of the first electrodes 4; only one liquid crystal lens unit 8 is shown in FIG. 1a, voltages applied to a plurality of first electrodes 4 in one liquid crystal lens unit 8 are symmetric with respect to a center position of the liquid crystal lens unit 8.
In order to reduce moire pattern, an extending direction of the strip-shaped first electrode 4 is usually set to have an included angle with respect to one edge of the first substrate 1. In an actual fabrication process of liquid crystal lens, rubbing directions of the first alignment layer 5 and the second alignment layer 7 are usually set to be parallel to one edge of the first substrate 1 or the second substrate 2. In this way, in the formed liquid crystal lens, there is an included angle between the rubbing direction of the first alignment layer 5 or the rubbing direction of the second alignment layer 7 and the extending direction of the first electrode 4. For example, in a liquid crystal lens having a structure shown in FIG. 1b, an included angle θ1 between the extending direction of the first electrode 4 and an edge a of the first substrate 1 is 18.43°, both the rubbing directions of the first alignment layer 5 and the second alignment layer 7 and light transmitting axial directions of the first polarizer 9 and the second polarizer 10 (a direction shown by a solid line arrow in FIG. 1b) are parallel to the edge a of the first substrate 1; when a pre-tilting angle of liquid crystal molecules is 2° and symmetric voltages shown in FIG. 1c are applied to the first electrodes 4, a cross-section b perpendicular to the extending direction of the first electrode 4 is selected for simulating, i.e., included angles θ2 between the selected cross-section b and the rubbing directions of the first alignment layer 5 and the second alignment layer 7 as well as the light transmitting axial directions of the first polarizer 9 and the second polarizer 10 are 71.57°, and a phase delay curve is obtained as shown in FIG. 1d, in which a horizontal coordinate represents a coordinate of a point on the liquid crystal lens, and a longitudinal coordinate represents a phase of the point, it can be seen that from FIG. 1d, the phase delay curve of the liquid crystal lens is obviously not symmetric, so the display quality of the liquid crystal lens when applied in 3D display will be significantly affected.